Acridines are an important class of chemicals which present a potential health hazard both to the general public and to workers involved in coking and fossil-fuel conversion operations. Many members of this class, including dibenz(a,h)acridine (DBAC) are potent carcinogens. The objectives of the proposed research are (1) to study the absorption, excretion, tissue distribution, and metabolism of dibenzacridine in mammals, (2) to assess the mutagenicity of DBAC metabolites, and (3) to investigate covalent binding of DBAC (and metabolites) with cellular macromolecues e.g., DNA, RNA and proteins, as the potential basis for its carcinogenic action. The metabolism of DBAC will be examined in rats both in vivo and in vitro, and the influence of enzyme induction, repeated exposure, and species variation on the metabolism of the chemical will be studied. It is expected that the results of this research will be useful in assessing the degree of health hazard presented by dibenzacridine and in understanding the mechanism by which the chemical acts. Also, dibenzacridine may serve as a model compound and the information gained from these studies may be useful in predicting the disposition and metabolism of other carcinogenic acridines.